Low potassium levels, also called hypokalemia, can affect people of all ages. Sometimes the condition is the result of a temporary condition--for example, if you perspire a lot during sports or intense exercise and you don't replace the water you've lost. For some people, hypokalemia is a chronic condition related to a disease or an eating disorder. Symptoms range from mild to severe, and extremely low potassium levels can be fatal.
Potassium is a mineral your body uses as an electrolyte, which means it carries an electrical charge. Potassium and other electrolytes--including sodium, phosphate, calcium and chlorine--are present in your blood and other bodily fluids. Your kidneys excrete these minerals from your body to maintain the correct balance. Electrolytes affect your blood chemistry and the functioning of your nerves and muscles, including your heart. Changes in the level of water in your body can make the levels of individual electrolytes either too high or too low.
A normal potassium level is between 3.5 and 5.0 milli-equivalents per liter--or mEq/L--of blood, according to Pennsylvania State University's Milton S. Hershey Medical Center. If your potassium is below 3.5 mEq/L, you have a condition known as hypokalemia, which means your potassium has dropped to a level that is of medical concern. A potassium level lower than 2.5 mEq/L can be life-threatening, the Mayo Clinic warns. Extremely low potassium may lead to cardiac arrest or paralysis of the lungs.
Low potassium levels can affect your muscles and may cause cramping, leg pain, muscle weakness and fatigue. Because of the relationship between electrolytes and your body's water level, you also may experience severe thirst, frequent urination or constipation. If your potassium levels are extremely low, you may develop paralysis, an irregular heartbeat, difficulty breathing and/or confusion. If your potassium levels are just slightly below the normal range, you may experience no identifiable symptoms, but over time, your body will produce less insulin, and your blood glucose levels will rise.
Potassium deficiency may be caused by anything that affects your body's water levels. For example, if you have a virus and you experience vomiting and diarrhea, your potassium levels may drop. Some medications, especially diuretics and laxatives, may disrupt your electrolyte balance. Certain diseases--including Cushing's syndrome, Padgett's disease, Fanconi's syndrome, Bartter's syndrome, primary aldosteronism, Liddle's syndrome and kidney disease--can cause low potassium levels. In addition, older people's kidneys don't function as well, and they are more prone to dehydration, which often leads to potassium deficiency. In rare cases, poor diet can cause low potassium levels.
If your potassium deficiency is slight or moderate, your doctor may recommend dietary changes or potassium supplements to increase your potassium levels and alleviate your symptoms. Tomatoes, oranges, bananas, spinach and other green, leafy vegetables are rich in potassium. Some sports drinks contain electrolyte replacements and may be helpful. If your low potassium levels are related to a medication you're taking for another condition, your doctor may switch you to another drug. If your electrolyte imbalance is severe, your doctor may hospitalize you so that you can receive potassium intravenously.